Long chain, heavy petroleum hydrocarbons in soils create a persistent environmental liability; these heavier fractions are less prone to natural weathering processes including volatilization, biodegradation, and dissolution. Since the early 1960s, nearly 6.8×108 kg of oil have spilled into United States soils from pipelines breaks or seepage from corroded lines. In addition, nearly 1.0×109 kg oil have spilled into United States marine waters, which often ends up on land unless contained or recovered after the spill. Of particular concern are petroleum residuals containing 12 to 40 carbon chain lengths (C12-C40) because of their low volatility and biodegradability.